County-level pesticide use and risk of congenital anomalies: a retrospective population-based study in Nebraska (1992 – 2014)
Exposure to agrichemicals has been linked to an increased risk of congenital anomalies. A previous study in Nebraska observed an association between single waterborne contaminants and birth defects. However, the joint association between pesticide mixture and birth defects has not been evaluated. This study examines the association of 32 commonly applied pesticides and congenital anomalies.We obtained data from the Nebraska Birth Defects Registry from 1995 to 2014. County-level pesticide-active ingredients from the United States Geological Survey, covering 1992 to 2014, were used for 93 Nebraska counties. The associations between 32 pesticides and birth defect subtypes were assessed using the Generalized Weighted Quantile Sum Regression (gWQS) model, adjusting for race, income, employment, and access to care. We observed a statistically significant positive association trend (P-value <0.05) between the 32 pesticides and birth defect subtypes. The strength of this association was slightly higher for craniofacial defects (β1=0.36, Std error 0.07) than for overall defects (β1=0.33, Std error 0.06), renal or genitourinary defects (β1=0.33, Std error 0.05), and cardiac defects (β1=0.32, Std error 0.05).Glyphosate, metsulfuron, quizalofop, triasulfuron, and efsenvalerate largely contributed to the joint association. Our findings suggest different patterns of joint associations for birth defects, providing further evidence of the effects of pesticide mixtures. Future research should prioritize individual-level studies to validate and extend these ecological associations.